Nail driving apparatus



March 26, 1968 R. B. DICKSON 3,374,934

NAIL DRIVING APPARATUS Original Filed Nov. 5, 1963 3 Sheets-Sheet 1 POWER 64 I74 58 h M 60 INVENTOK ROBERT B. DIOKSON March 26, 1968 R. B. DICKSON NAIL DRIVING APPARATUS 3 Sheets-Sheet 2 Original Filed Nov. 5, 1963 R W W W ROBERT B. DICKSON 6% ATT'Y.

United States Patent 3,374,934 NAIL DRIVING APPARATUS Robert B. Dickson, Evanston, Ill., assignor to Dickson Weatherproof Nail Company, Evanston, 11]., a corporation of Delaware Original application Nov. 5, 1963, Ser. No. 321,450, now Patent No. 3,212,622, dated Oct. 19, 1965. Divided and this application Aug. 19, 1965, Ser. No. 481,003

13 Claims. (Cl. 227130) ABSTRACT OF THE DISCLOSURE A nail driving tool in which nails are fed thereto along a helical path with their heads contacting each other and defining a cylindrical surface of revolution with their shanks also contacting each other at the axis thereof. The lead nail is helically guided into a poised position with its head partially intruding in a bore in which a piston is reciprocated manually to discharge the nail into the bore and a power driven hammer advances the nail with repeated blows on the piston step by step as the handle is moved towards a work piece keeping the piston in contact with the nail. The piston includes a nail set stem therein which is reciprocated with respect thereto by relative rotation induced by movement of the handle. The leading nail can be retracted from its poised position for tool storage to clear the piston in its fully advanced position in which it is locked when not in use.

The present invention is a division of application Ser. No. 321,450, filed Nov. 5, 1963, now Patent No. 3,212,622 issued Oct. 19, 1965 and relates to power driven nailing equipment in which nails, particularly common nails, both loose and in clips are received in a bore ahead of a piston and driven into a workpiece preferably with repeated blows of an automatic hammer.

Power equipped devices have been used for many years for driving nails and brads. Many problems have beset the industry requiring the provision of special nails and magazinesinclined to the driving barrel. Expensive strips, wire, webbing or adhesive tapes have been resorted to in order to space the nail shanks and maintain the nail heads in coplanar relationship for straight line feed applications.

An object of the invention is to provide a nailing gun which fits in with and utilizes the skills of a journeyman to drive and set nails without marring the wood yet can rough-hammer nails home without unsightly marring of the wood surface.

A further object of the invention is to provide visual, tactual and auditory perception as to the speed and depth at which each nail is being driven in order to capitalize upon the skill of the journeyman for neat and mar-free work as distinguished from the results of a heavy oneblow drive.

The invention is also characterized by the hammer being advanced and the device guided by one hand and the nail as it is being driven. The depth that the nail advances is followed visually so that the last few blows can be controlled to leave the nail head at whatever level desired.

A further object of the invention is to provide a resting status for a power nailer which prevents movement of the next nail from the magazine into the driving chamber until after actuation of the device whereupon release is immediately accomplished followed instantly by the first of a series of nail driving hammer blows with continuous contact being maintained between the nail and the driving element struck by the hammer.

Another object of the invention is to provide a pneumatic nailer in which the nail feed and driver characteristics are unchanged by environmental forces regardless in which position the device is operating.

Another object of the invention is to provide a power driven nailer which handles common and finishing nails and can terminally set either nail with force-tempered blows as controlled for each nail or nail size individually by the operator.

The invention also contemplates ready interchangeable use of electrically driven or pneumatically powered hammers depending upon which type hammer is readily available, or which form of power is available.

Another object of the invention is to provide a gun which drives common nails at any usually employed angle ranging from to a toenailing angle of studs on joists with or without suitable adaptor shoes for particular purposes.

Another object of the invention is to provide a portable, light, power driven nailer that is easily managed by one hand, utilizes electricity or fluid pressure as a power source interchangeably is comparatively inexpensive, and is easy to service and maintain.

Further objects of the invention will appear from the description which follows and the drawings related thereto in which:

FIGURE 1 is a side elevational view partly in section taken longitudinally and centrally through a portable power nailer embodying the invention.

FIGURE 2 is a cross sectional view taken through the bore and feed chamber of the nail driving elements at approximately the level of the nail heads entering the bore for driving purposes.

FIGURE 3 is a section taken upon line 3-3 in FIG. 2.

FIGURE 4 is a section taken on line 4--4 of FIGURE 1, and

FIGURE 5 is a partial section similar to FIGURE 1 showing the nail setting relation.

The invention is illustrated in connection with nails that are most used. Such is the common nail that ranges from 1.5 to 2.5 inches in length and the nail 10 particularly disclosed is an eightpenny common nail approximately 2.5 inches long with a wire shank diameter of .28 inch. For ready handling the nails are arranged in clips 12 of ten nails each (FIG. 1) in which the shanks 14 contact a little off-center their midpoint in a straight line 16 sometimes referred to herein as an axis and the heads 18 contact edge-to-edge at their periphery in a helical path with their top surface 20 following a cylindrical surface of revolution 22.

Although both contacting areas of adjacent nails at their heads 18 and at the center line 16 may be adhered with a frangible cement 30, it has been found that adherence at the center line contacts of the nail shanks is preferable and adequate.

The helix angle is one of approximately 35 and although the clips may be formed to a full helical turn or any part of a full turn, it is preferred to furnish them in units of ten nails each. This provides a little less than a 90 turn for each of two clips shown in FIG. 1. The heads are about twice the diameter of the shank. In this size and number they are easy to count, assemble, handle and package.

With portable power tools such as shown at 52 in FIG. 1, the clips can be hand inserted one or more at a time into the track 44 in magazine 42. The magazine will take at least four clips, preferably six to eight. Four clips will supply a magazine of 40 nails and a six to seven inch magazine provides a starting charge of half a hundred nails plus any partially used clip already present. Moreover, it will be appreciated from the description herein that loose common nails can also be fed into the magazine 42 if desired at any time as a group or intermingled between clips.

The helically shaped track 44 is peripherally supported on the main housing 54 to receive nail clips 14 in helically aligned and guiding relationship. The plan contour of the nail adjacent to and including the head 18 (FIG. 3) is approximately in the cross-sectional contour of the track and preferably is defined by an elongated element having a T-groove 86 therein, the element preferably is rolled from straight stock like a helical spring into a helix in which the head portion 88 of the groove defines a helical lead angle of approximately 35 and the space between the legs 90 of the T-groove define a helix angle, of 45 or more, leaving approximately one-third to one-half of the length of the nail shank 14 exposed at the center of the housing 54. If a 2.5 inch nail is fed, a center third portion of the shank will be exposed. If a 1.5 inch nail is fed, it will be the terminal portion of the shank that is exposed. If the nail heads 18 are twice the diameter or more of the shank 14, the head helix angle will be 35 or less accordingly. If the heads 18 are less than twice the diameter of the shank 14, a magazine helix of 35 will still take the nails with the clip provided with a 35 helix angle.

At the inner end 92 of the track 44 the endmost nails 10a pass successively one at a time from the track 44 into a guide block 94 (FIG. 2) carried by the housing 54 and into terminal engagement with a vertical shoulder 96 that aligns the shank of the nail in parallel relationship with the bore 62 in the barrel 60. The nail in this position has the lower or point end disposed where it enters or is cammed as at 98 (FIG. 3) into the bore 62. The head 18 of the nail protrudes into the bore 62 and when the drive piston 100 is forced from its poised position downwardly in the bore 62 the nail head is engaged and displaced. The nail 10 is thereby broken free of its cement and stop restraints and is carried radially inwardly and downwardly in the bore. The point 24 strikes and starts itself in the work 50 after which repeated blows upon the piston 100 forces the nail deeper and deeper without contact between the piston and nail head being relinquished until the nail has been driven to the depth desired.

- More particularly, in FIG. 2 it will be observed that the bore 62 is hexagonal and the barrel 60 is broached at a tangent to the bore to provide a rectangular opening 102 therethrough as wide as the widest width of the T-shaped track 44. A block 104 is then made with a corresponding T-groove 88a therein abutting the track end 92 in alignment therewith as guided by two ears 106 which telescope over the sides of the leg portion 44a of the track 44 just below the head portion thereof. The block may be made of two elements fused or riveted together to provide tangential intersection of the bore 62 with a T-slot 86a having a lateral discharge opening at 108 disposed radially to the bore 62.

A T-shaped stop member 110 is slidably received in the block 104 beyond the lateral opening 108 therein and has a squared end which carries the stop 96 slidably in the T-groove 88a to limit movement of the endmost nail head indicated at 18a. Assuming the axis of the endmost nail as so limited, the block 104 is carved by a side cutting tool (not shown) below the head 18a to provide a coaxial conical cam 112 (FIG. 3) which shifts the head 18a fully into the bore 62 as it is moved downwardly by the piston, first to clear the squared end stop 96 and then downwardly across the cam surface 112.

Below the block, the wall 114 of the housing 54 is milled out to provide a full access opening 116 for the endmost nail to come into parallel relationship with the bore and a like coaxial cam or chamber 98, as already mentioned, is provided at the bottom thereof to assure movement of the lower end of the nail fully into the bore 62 when the nail head is moved downwardly initially by the piston 100.

For the occasions when it may be desirable to actuate the piston 100 without injecting a nail 10a into the bore, the slide member 110 (FIG. 2) may be pushed by a button 118 to move the squared stop 96 and force back the endmost nail 10a from its ready position intruding in the bore 62. For this purpose the outer end of the rectangular opening is plugged with a block 120 held in place by a set screw 122, is bored at 124 and internally threaded at 126 to receive an adjustable sleeve 128. The sleeve 128 has a stop 130 thereon for the slide block 104 and a spring guide for a compression spring 132 that urges the slide block towards the oncoming nails when the endmost nail 10a has been discharged from the delivery portal made up of openings 108 and 116. A push rod 134 threaded to the slide block 104 carries the button 118 on the end thereof and thereby further serves as a telltale as to whether or not a nail 10a is in delivery position. The slide block is milled out along the contour 136 to clear the drive piston 100 regardless of the position of the slide block 104.

It will be observed that while a nail 10a is being driven, the piston 100 wall holds back the next nail 10 until the piston is retracted. During this time the slide block 104 moves towards the incoming nail under the mild influence of the spring 132 and tool vibration and makes contact with the head 18 thereof so that it is somewhat guided and constrained in attaining and remaining in delivery position after the piston is retracted. Adjustment of the sleeve 128 and stop 130 assists in positioning the end nail 10a. In this connection it will also be observed with nails having different head siZes that the tangency of the nail advance is such that a portion of the shank 14 diameter also intrudes into the bore 62, as seen in FIG. 1, thereby assuring by this adjustment that nails having the smallest of heads for a given shank size can be driven.

In the event the operator permits the piston 100 to return to a position above the next nail head 18 and he desires to finish driving the previous nail, the slide block 110 and stop 96 are moved as controlled by a button 118 to drive the end most nail head back out of the path of movement of the piston thereby permitting the piston to be lowered to resume driving the previous nail, or, to permit merely a pounding action without movement of any nails being involved. Release of the button 118 permits resumption of the successive removal and driving of further nails from the magazine.

Considering now the driving of the nail, the piston 100 is initially moved in the barrel 60, preferably by hand through downward movement of the handle 180, and is concavely shaped on the lower end at 137 (FIG. 3) to assist in centering the nail head 18a. Furthermore, in the preferred embodiment the piston is bored to receive a nail setting stern 138 which in resting position does not engage a flat nail head, but when the handle 180 piston 100 is rotated a quarter turn, as hereinafter described in connection with FIG. 4 for relative movement of segments 164 and the bumper 166, the nail set pin 138 does engage the nail head as will shortly be described in connection with relative rotation between the piston 100 and nail set 138.

In providing this, a windowed guide housing 140 (FIG. 1) is threaded in the flange 64 on the main housing and has an inwardly directed radial flange 142 on the housing 140 at. the head 144 of a power cylinder or housing 148 which is spring pressed outwardly i.e., to a retracted position, by a conical compression spring 146.

The lower face of the power cylinder 148 has a spring 153 receiving socket 150 whose side walls 152 serve as a stop engaging a washer -154 on the drive piston 100 above which the piston 100 is cylindrical, as at 156, to permit relative rotation between the piston 100 and the power cylinder 148. The corners of the hexagonal con tour therebelow provide shoulders supporting the washer 154. Thus, the spring 153 urges the piston 100 downwardly while the main spring 146 holds the power cylinder upwardly. The piston 100 however becomes captive to manual downward movement by the handle and cylinder 148 when the washer 154 walls 152. a

This arrangement provides several novel results, the piston 100 can be manually disposed in an interference path for the end most nail a if desired by merely moving the head 144 downwardly a short distance away from the flange by a relatively rotatable axial cam means at 155, or preferably moving it manually all the way down where a bayonet lock between lugs 160 at the bottom of the housing 140 and slots 162 in the head'144 can hold them for storage. Either or both, however, can be used. Once the cam 155 or lock 160 is released the piston 100 is spring raised to clear the nail head 18a and thereafter downward pressure on the power cylinder frees the endmost nail 10a and maintains contact therewith while actuation of the hammer drives the nail. Concomitant therewith the arrangement provides the opera tor not only with a visual perception of progress through windows 158, but also tactual perception of the driven movement of the nail. 8

Referring now to the relative manual rotation between the piston 100 and nail set 138, the piston is preferably hexagonally shaped externally at its lower end for nonrotational guidance by the hexagonal bore 62. Thus, relative rotation is established for manual control between the power cylinder 148 and the head 1004 on the piston 100 in the cylinder 148. The head 100a is held against rotation when the handle 180 rotates the cylinder 148. Means are then provided whereby the nail set stem 138 can be rotated by rotary movement of the power cylinder so that the nail set is activated for setting nails driven by the piston 100. For this purpose the nail set stem has quarter segments 164 matable 'With but normally resting on top of quarter segments 168 on the head 100a carried by the piston 100, As thus disposed, nail driving effort is transmitted through the 'segments'to the piston 100 and thereby to the nail head without the nail seat protruding. However, with a quarter turn of the power cylinder, the segments of both elements interdigitate to drop the nail set stem 138 downwardly to protrude and deliver a final driving blow to thefnail head through the nail setstem. The rotation of the nail set 138 by the cylinder 148' is accomplished through the conbottoms on the side struction of the upper face of a rubber bumper 166 that is provided to cushion any blow not transmitted in full toa nail head. The bumper 166'is fit tightly in the cylinder 148 at its base and the cushion portion has-upstanding guide ways 189 receiving in rotary engagement radial ears 170 on the bottom nail set stern head segments 164. Thus, relative rotation between the nail set stem and piston 100 can be accomplished by rotation of the cylinder 100 while the hexagonal bore 62is stationary when desired. The nail set feature can beomitted or removed at any time or in any construction merely by omitting the nail set stem. 1

The power unit and piston are removable at the threaded joint on flange 64, the spring 146 being retained therewith as bottoming on a C-fiange spring 172 resting in groove 174. Thus, an electrical or pneumatic hammer means can be interchangeably used with the magazine shown or interchangeable with a series of magazine similarly constructed to take different nail size ranges merely by unthreading at the jointt.

Preferably the upper end of the power unit hasa pistol grip handle 180 and actuation of the-device is by trigger 182, in any suitable manner, accompanied by .downward force. on the handle 180. In this connection downward force on the handle raises the piston head 100a off of the bumper 166 against the action of the sprint 153 so that the full blow of the hammer'is transmittedto the nail. The distance of this movement can be manually varied depending on the power of each hammer blow desired for the ranges of nails to be handled and the final blows. Letting up on the handle until. some of the. blow is cushioned by the bumper lightens the blow delivered.

It is desirable to strike eight to twelve blows before the final blows in order for the operator to have time to reach to let-up and lighten the final few blows if desired. It was noted that initial downward thrust on the power cylinder severs and moves the nail into driving position, if desired, before. moving the trigger to apply the first hammer blow. This is particularly desirable for shorter nails to place the nail and hammer into operating relationship before a power stroke blow is induced. Thus, operation of the device is versatile for operation by differently skilled workmen anddifferent sizes of nails. A hammer 184 conventionally reciprocated electrically either by electro .magnet or motor is shown, as by way of example, but not to exclude pneumatic hammers as controlled by the trigger switches 182.

Considering further the action and control of driving the nails, indicator marks 185 (FIG. 1) encircling either cylinders or 148 serve as references between them to indicate the remaining position of the nail as seen from any direction. This is true of and is constant for all nail lengths.

In operation, once the clips of nails are located in the track 44 with the spring 46 urging the leadmost nail 10a to the discharge portal at opening 116 with the head 18a against the block 110, the handle is manually gripped and forced downwardly to move the drive piston to engage and displace the head 18a and nail 10a downwardly. Cam surfaces 98 and 112 center the nail in the bore 62 andfingers 70 locate the point 24 in position against a work piece 50. The trigger 182 is then actuated energizing the drive means for propelling the hammer 184 downwardly against quarter segments 164 which rest on top of the quarter segments 168 on the head 10011 of the piston 100 and a blow is delivered to the nail head 18a to start it into the work piece whereafter' further actuation of the trigger operates to drive the piston 184 until the nail is driven out' of the 'foot 192. Thereupon, if desired, the handle 180 is rotated until the quarter segments 164 rotated by guideways 189 interdigitate with the segments 168 as held against rotation by the hexagonal contour of the piston thereby extending the nail set 138 beyond the bottom of the piston. Further hammer blows then actuate the nail 'set to embed the nail head in the work piece. The-handle is then raised and returned to the original relative rotational position and the device is ready for a repeat operation.

Whenever it is desired to store the device pressing the button 118 retracts the nail head 18a, clearing the bore 62 whereupon; the handle is pushed all the way down and turned for the bayonet joint means 160 to engage after which the pistonoccupies' the bore 62 holding the nail head 18a in its retracted position.

As the head of the endmost nail 10a is severed from the clip and moved downwardly, it clears the shank of the next'nail 10 by the cams described but preferably before the point 24a'of the nail cont-acts the work the downwardly inclined spring fingers 70 center the point; As the nail is-d'riven home the head 18a thereof clears the fingers and the lower end of the piston 100 holds them outwardly until the piston is retracted for the next nail. Any time a nail head requires a few more driving blows to seat it the piston is moved down through the spring fingers to engage the nail and strike the blows without damage to the spring fingers because one of the features of the invention is that the piston during the driving operation is held in contact with the nail head being driven all the way down. ,The lower end of the boss 60 preferably is threaded at 190 to interchangeably receive shoes. A standard shoe 192 that is rounded to prevent surface scratching is illustrated. Specially constructed shoes can be used for special application and angles and can include guides or .even nail: pulling teeth. The one which is standard for the embodiment disclosed is provided with four short ribs 194 with indicia lincs.195 at right angles to each other to to better center it with respect to a particular spot or nail entrance opening when desired.

While common nails are disclosed in the drawing and the description relating thereto it will be understood that any form of nail having a head diameter larger than the shank can be handled by devices embodying the invention, including spikes, roofing nails, brads, finishing nails, etc. and further than frangible bonds other than cement can be employed including plating material, soft wires fused thereon, or tapes, provided they hold the shanks in contact with each other where they cross.

Having thus disclosed and described the invention, it will be readily apparent how the stated'objects and other objects and advantages set forth are accomplished and how various and further changes can be made therein without departing from the spirit oi, the invention, the scope of which is commensurate with the, appended claims.

What is claimed is:

1. A nail driving machine adapted to receive nails in a helical path with adjacent heads in edge contacting relationship and other adjacent shanks contacting comprising a housing having a bore, a nail driving piston reciprocable in said bore, a portal in the wall of the bore at the discharge end of the helical path for receiving laterally therethrough the head of the leadmost nail in said helical path in a direction tangential to said bore with the head supported partially through said portal into the path of said piston, manual means for advancing said piston to engage said head and move said leadmost nail downwardly removing the shank of the leading nail from contact with the shank of the next nail, radial cam means in said wall adjacent to said portal for moving the head and shank of said leadmost nail fully into the bore upon downward displacement of the head by said piston, and means for delivering a repeated number of blows to said piston to drive the nail from said bore.

2. A nail driving device adapted to receive nails in a helical clip in which the shanks of adjacent nails contact in angular relationship and frangible means hold them in said contacting relationship, said device comprising a housing defining a bore, a nail driving piston reciprocable in said bore means for delivering a plurality of nail driving blows to a nail in the bore, means for feeding said nails towards said bore along a helical path, a portal in the wall of the bore at the discharge end of the helical path for receiving laterally therethrough the head and shank of the leading nail of said clip, means for feeding said clip along advancing the head of the leadmost nail partially through said portal, stop means opposing further movement of said head through said portal, said frangible means supporting the shank of said leadmost nail parallel to and alongside said bore, manual means for advancing said piston to engage the head of the leadmost nail and break said frangible means supporting the shank, and radial cam means for moving the head and shank of the leadmost nail fully into the bore upon downward displacement of the head by said piston.

3. The combination called for in claim 2 in which said stop means is movable in said housing, resilient means urging said stop means to engage the head of the next leadmost nail before it enters the portal, means for adjusting the location of said stop means, and manually actuated means for moving said stop means to retract the leadmost nail from the portal at will.

4, A nail driving device adapted to receive nails in a helical path comprising a housing defining a bore with a nail portal in one side thereof at the end of said path, a power cylinder reciprocable in said housing, piston means carried by said power cylinder reciprocably in said bore, resilient means urging said power cylinder to a resting position in which said piston means is poised above said portal, stop means for restraining a nail in position at said portal'with its head partially in said bore to be engaged by said piston upon downwardly movement thereof, means limiting relative movement between said power cylinder and piston for displacing said head into said bore by said piston upon movement of the power cylinder from its resting position, and means for driving said piston with repeated blows to propel said nail into a workpiece at the end of said bore.

'5. A nail driving device adapted to receive nails in a helical path comprising a housing defining a bore with a nail portal in one side thereof atthe end of said path, a power cylinder reciprocably carried by said housing, piston means carried by said power cylinder reciprocably in said bore, resilient means urging said power cylinder to a resting position in which said piston means is poised above said portal, stop means in said housing for restraining a nail in position at said portal with its head partially in said bore to be engaged by said piston upon downwardly movement thereof, means limiting relative movement between said power cylinder and piston for displacing said head into said bore by said piston upon movement of the power cylinder from its resting position, means for driving said piston with repeated blows to propel said nail into a workpiece at the end of said bore, said piston means including an outer member and an inner longer member defined in telescoping relationship and rotatable with respect to each other from one relative position of engagement in which said inner member is withdrawn within the outer member to another relative position in which said inner member extends beyond the outer member and into the bore, means for holding one of said members against rotation with respect to said power cylinder, and means for rotating the other with respect thereto from one relative position to the other.

6. A nail driver comprising a main housing defining a bore having a portal for receiving a nail with its head partly in said bore, a guide housing secured to the main housing concentric with said bore, a hammer housing slidably mounted axially on said guide housing and carrying a piston coaxially with said bore, said piston being slidably mounted with respect to said hammer housing, bumper means in said power housing normally engaged by said piston, means carried by said hammer housing for limiting movement of said piston away from said bumper to hold the piston in engagement with a nail in said bore upon movement of the hammer housing toward said bore, and resilient means carried by said guide housing urging retraction of said piston from engagement with said nail in the bore.

7. A nail driver comprising a main housing defining a bore having a portal for receiving a nail with its head partly in said bore, a guide housing secured to the main housing, a hammer housing rotatably and slidably mounted on said guide housing and carrying a piston coaxially with said bore, said piston being slidably mounted with respect to said hammer housing, bumper means in said hammer housing normally engaged by said piston, means for limiting movement of said piston away from said bumper to hold the piston in engagement with a nail in said bore upon movement of the hammer housing toward said bore, and resilient means urging retraction of said hammer housing and the piston from engagement with said nail in the bore, said piston means including telescopmg outer and inner members rotatable with respect to each other from one relative position of interengagement in which the inner member is withdrawn within the outer member to another in one relative position in which said inner member extends beyond the outer member within the bore, means for holding one of said members against rotation with respect to said power cylinder, and means for rotating the other with respect thereto.

8. The combination called for in claim 6 including a coupling means between said guide housing and hammer housing for holding said piston in position obstructing said portal during nonuse.

9. A nail driver comprising a main housing defining a bore having a portal for receiving a nail therethrough in said bore, a guide housing secured to the main housing, a hammer housing rotatably and slidably mounted on said guide housing and carrying a piston coaxially with said bore, said piston being slidably mounted with respect to said hammer housing, bumper means in said hammer housing normally engaged by said piston, means for limiting movement of said piston away from said bumper to hold the piston in engagement with a nail in said bore by movement of the hammer housing, resilient means urging retraction of said piston from engagement with said nail in the bore, means for supporting the piston against rotation with respect to the main housing, a nail setting stern reciprocably and rotatively carried by said piston, means for supporting the nail setting stem against rotation with respect to the hammer housing, and cam means between said piston and stem for extending the lower end of said stem beyond said piston upon relative rotation between said hammer housing and main housing a predetermined angular distance.

10. In a power driven nailing machine, a housing defining a bore for receiving a nail therein, a piston for driving said nail from said bore, means for reciprocating said piston, a nail setting element carried by said piston and movable axially with respect thereto, means for protruding said nail setting element below the end of the piston to set a nail driven by said piston.

11. In a power driven nailing machine, a barrel having a bore for receiving a nail therein, a piston for driving said nail reciprocably in said bore for reciprocating said piston including a handle and a return spring, a nail setting element carried by said piston and movable axially with respect thereto, means for protruding said element below the end of the piston to set a nail driven by said piston, and manually controlled hammer means for driving said piston and stem.

12. A nail driving device adapted to receive nails in a helical clip in which the shanks of adjacent nails contact in angular relationship and frangible means hold them in said contacting relationship, the combination of a housing having a bore therethrough having a nail portal laterally through the wall of the bore admitting the leadmost nail to said bore, means for holding the leadmost nail with a portion of its head intruding in said bore and said frangible material supporting the shank of the leadmost nail in contact with the shank of the following nail at the axis of said helical path, a nail driving piston slidably mounted in said bore for engaging said intruding portion, manual means for advancing said piston to release said frangible material and holding said piston against said nail to discharge it into said bore through said portal, and means for delivering repeated blows against said piston so held to drive the nail contacted thereby into a workpiece;

13. In a power driven nailing machine adapted to receive nails in a helical path with their adjacent heads in edge to edge contact and their adjacent shanks in contact at the axis of said helical path, the combination of a housing having a bore therethrough with a nail portal laterally through the wall of the bore admitting the leadmost nail to said bore, stop means for holding the leadmost nail intruding into said bore, a nail driving piston slidably mounted in said bore for engaging said intruding portion, means movable manually for advancing said piston against said nail to dislodge it and carry it into contact with a workpiece, and means for delivering hammer blows against said piston to drive the nail into the workpiece including a hammer carrier reciprocably mounted with respect to said piston.

References Cited UNITED STATES PATENTS 1,554,128 9/ 1925 Robertson. 2,857,596 10/1958 Allen et al. 2,982,595 5/1961 Rogers 227136 3,157,884 11/1964 Decot et al 227-136 GRANVILLE Y. CUSTER, 111., Primary Examiner. 

